As soon as the amino acid sequence of GIP is obtained, the gene for GIP will be constructed and expressed in E. coli to produce a large amount of GIP. As designed and synthetic promoter will be cloned in E. coli and used for the expression of synthetic genes for peptide hormones. A gene for secretin will be designed, synthesized and expressed in E. coli. For the studies of the structure-function relationship of insulin, radioactive insulin derivatives and insulin analogues will be produced using recombinant DNA techniques.